The first light of the observable universe and the traces of the first moments of creation came down to us. The universe by definition contains all that exists, including the space-time, it is therefore not a "border". Indeed, the existence of an border would imply that beyond this border, there would be more in the universe, come us cross this observable limit?
This observable limit, is a radio whispers captured by different satellites, in the electromagnetic spectrum at 2.7 K (-270 ° C).
It shows us the residual fluctuations of our universe and filigree, lumps of matter that gave rise to galaxies, the stars and all that we currently see.
It is through the fossil electromagnetic radiation or Sky background, detected incidentally by Arno Allan Penzias and Robert Woodrow Wilson in 1965, we can see our past. Ralph Alpher and Robert Herman supported by George Gamow had predicted in 1948 the existence of an residual from the Big Bang radiation.
The Big Bang model emphasizes the existence of a phase of very short cosmic inflation, but during which the universe would have grown extremely rapidly. It is from here that most of the material particles of the universe were created, high temperature, prompting the issuance of a large amount of light, called the cosmic microwave background. This radiation is observed today with great precision by space probes.